In a conventional terminal joining structure for high current usage and a terminal joining method therefor, a flange portion is formed at one end of a tubular terminal body and a pair of protrusions are formed at the outer periphery of that end of the terminal body which is on the opposite side of the flange portion. Besides, a hole for inserting the tubular terminal body is formed on a conductor substrate and grooves through which the protrusions can pass on the inner surface of the hole are formed. Upon inserting the terminal body in the hole, the terminal is rotated for shifting the positions of the projections and the grooves out of alignment so that the conductor substrate is sandwiched between the projections and the flange portion. In that condition, the terminal body is soldered to the conductor substrate. Thus, the terminal body is fixed to the conductor substrate by performing clamping using the projections and the flange portion and performing soldering (e.g., see Patent Literature 1).    Patent Literature 1: Japanese Patent Application Laid-open No. H7-249882